Copper minerals
Copper minerals are a group of minerals, which contain the copper element in their chemical composition. Here are some important copper minerals;
(1). Azurite: Cu3(CO3)2(OH)2
Physical Properties:
- Crystal System: monoclinic
- Cleavage: Perfect prismatic cleavage
- Hardness: 3.5 – 4.
- Specific Gravity: 3.77
- Lustre: Vitreous
- Colour: Azure-blue
- Streak: pale-blue
- Habit: Crystalline. Also in radiating groups or massive.
Occurrence:
It occurs as a secondary mineral. It frequently alters to malachite.
Uses of Azurite:
- Azurite having a shining blue colour, is used in jewellery, beads and ornamental stone.
- Azurite is used as an ore of copper.
(2). Malachite: Cu2(CO3)(OH)2
Physical Properties:
- Crystal Systems: monoclinic
- Cleavage: perfect but rarely seen
- Hardness: 3.5 – 4
- Sp.Gr: 3.9 -4.03
- Lustre: vitreous in crystals, silky in fibrous varieties and dull in massive varieties.
- Colours: Bright green
- Streak: pale green
- Habit: Usually in radiating fibres forming botryoidal or stalactitic masses. Also granular or earthy.
Occurrence: Malachite is a secondary copper mineral found in the zone of oxidation of copper veins.
Uses of Malachite:
- Malachite is used as an ore of copper.
- Used as gemstone, and in jewellery.
- Used in small sculptures.
- Being green in colour, malachite is used as a pigment.
(3). Cuprite: Cu2 O
Physical Properties:
- Crystal Systems: cubic
- Cleavage: poor cleavage
- Fracture: uneven
- Hardness: 3.5 – 4
- Lustre of Cuprite: metallic
- Colours of Cuprite: copper red, tarnishing to purple iridescent.
- Streak: grayish black.
- Habit of cuprite: usually massive
Occurrence:
Cuprite is found in the upper oxidized portions of copper veins. It is often associated with native copper, malachite and azurite.
Uses of Cuprite:
- Cuprite is used as an important ore of copper.
- Cuprite crystals are transparent to translucent and red to a deep red that can appear almost black. For jewellery, cuprite is mostly used as cabochons and beads.
- Cuprite is used as a colorant to produce ruby red glass.
(4). Bornite: Cu5FeS4
Physical Properties of Bornite:
- Crystals Systems: cubic
- Cleavage of bornite: absent
- Fracture: Uneven
- Hardness: 3
- Sp. Gr. 5.06 -5.08
- Lustre: metallic
- Colour: copper red, tarnishing to purple iridescent.
- Streak: greyish black.
- Habit: usually massive
Occurrence of Bornite:
Bornite is commonly found in hydrothermal ore deposits.
Uses of Bornite:
- Bornite is used as copper ore.
- Metaphysically bornite is said to bring good luck and joy to life.
- Bornite is used as an eye-catching piece in homes, offices, and other places.
- Being too soft, bornite is not used in jewellery.
- It contains iron in its chemical composition, therefore, it may be used as iron ore.
- Bornite can give Cupric Sulfide on dissolving in Sulfuric acid.
(5). Chalcopyrite: CuFeS2
Physical properties of Chalcopyrite:
- Crystal System of Chalcopyrite: tetragonal crystal system
- Cleavage of Chalcopyrite: poor cleavage
- Fracture: uneven
- Hardness of Chalcopyrite: 3.5 -4
- Sp.Gr. of Chalcopyrite: 4.28
- Lustre of Chalcopyrite: metallic
- Colours: brass yellow.
- Streak of Chalcopyrite: greenish black
- Habit: Crystals show tetrahedral shape. Also massive and compact.
Occurrence:
Chalcopyrite is the commonest copper mineral. It is found in hydrothermal veins. It is associated with pyrite and other sulfides.
Uses of Chalcopyrite:
- Chalcopyrite, while containing copper and iron, is used as an ore of iron and copper.
- Some deposits of chalcopyrite contain zinc.
- Some chalcopyrite contains a sufficient amount of gold and silver.
(6). Chalcocite: Cu2 S
Physical Properties of Chalcocite:
- Crystal System: orthorhombic
- Cleavage of Chalcocite: poor
- Fracture of Chalcocite: Chalcopyrite has conchoidal fracture.
- Hardness: 2.2 – 3.0 on Moh’s scale
- Specific Gravity: 5.77
- Lustre: metallic
- Colour and streak: dark grey.
- Habit: Short prismatic crystals. Also massive
Occurrence:
Chalcocite is formed by the alteration of primary copper sulfides in zones of secondary enrichment.
Uses of Chalcocite:
- Chalcocite is an important source of copper and iron because extracting the copper from the sulfur in Chalcocite is relatively easy.
(6). Covellite: CuS
Physical Properties of Covellite:
- Crystal System: hexagonal crystal systems
- Cleavage: perfect giving flexible plates.
- Hardness: 1.1 -2.
- Sp.Gr. 4.6 -4.76
- Lustre: metallic, massive varieties dull.
- Colour: indigo blue
- Streak: dark gray, shining
- Habit: platy crystals usually massive.
Occurrence:
Covellite is found in the zone of sulfide enrichment. It is associated with other copper minerals, such as chalcocite, chalcopyrite, bornite, etc.
Uses of Covellite:
Covellite is used as an important ore of copper.
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